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HAEMATOLOGY > Bleeding and coagulation > Flashcards

Bleeding and coagulation Flashcards

1
Q

What is haemostasis?

A

The arrest of bleeding and maintenance of vascular patency

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2
Q

What is primary and secondary haemostasis?

A

Primary haemostasis is the formation of a platelet plug

Secondary haemostasis is the formation of a fibrin clot

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3
Q

Where are platelets formed?

A

Platelets are formed in the bone marrow by budding from megarokaryocytes

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4
Q

What is the life span of a platelet?

A

7-10 days

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5
Q

What are some of the possible causes of failure of platelet plug formation?

A

Vascular causes
E.g reduced collagen in blood vessels in elderly patients and inherited causes such as marfan’s

Thrombocytopenia due to anti-platelet medications and NSAIDs

Von Willebrand disease

Lack of vitamin C e.g scurvy

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6
Q

Which is generally more severe, failure of primary haemostasis or failure of secondary haemostasis?

A

Failure of secondary haemostasis

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7
Q

How does failure of platelet plug formation present?

A

Spontaneous bruising and purpura (usually in the lower limbs due to gravity)

Mucosal bleeding (epistaxis, GI, conjunctival and menorrhagia)

Intracerebral bleeds in severe cases

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8
Q

What is the screening test for primary haemostasis?

A

Platelet count

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9
Q

What are the screening tests for secondary haemostasis?

A

Prothrombin time

Activated partial thromboplastin time

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10
Q

What are some of the naturally occurring anticoagulants?

A

Anti-thrombin

Protein C and S

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11
Q

Does prothrombin time test the extrinsic or the intrinsic pathway?

A

Extrinsic pathway

It measures the propagation side of fibrin clot formation

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12
Q

What is the normal range for prothrombin time?

A

12-13 seconds

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13
Q

What are some of the causes of a prolonged PT?

A

Warfarin therapy

DIC

Liver disease

Vitamin K deficiency (premature babies and ITU patients)

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14
Q

Does the APTT test the extrinsic or the intrinsic pathway?

A

Intrinsic pathway

Measure the amplification side of fibrin clot formation

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15
Q

What is the normal range for APTT?

A

30-40 seconds

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16
Q

What are some of the possible causes of prolonged APTT?

A

Heparin therapy

Haemophilia

VW disease

Antiphospholipid syndrome

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17
Q

Thrombocytopenia is the most common cause of primary haemostatic failure. What are some of the possible cause of thrombocytopenia?

A

Cancer

DIC

Immune thrombocytopenic purpura

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18
Q

What is immune thrombocytopenic purpura?

A

An autoimmune cause of thrombocytopenia which involves antibodies against platelets

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19
Q

how is immune thrombocytopenic purpura managed?

A

Prednisolone (steroids)

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20
Q

VWF deficiency can be acquired or hereditary. Which is more common?

A

Mostly hereditary

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21
Q

What mode of inheritance does VWF disease involve?

A

Autosomal dominant

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22
Q

VWF affects men and women equally, so why are men less likely to be diagnosed?

A

Women are more likely to present as they may have the symptom of menorrhagia

The condition may not become apparent in men until they have an accident or operation and notice abnormal bleeding

23
Q

Is haemophilia due to a single or multiple clotting factor deficiencies?

A

Single clotting factor deficiency

24
Q

Where are coagulation factors synthesised?

A

In hepatocytes in the liver

25
Q

What happens to coagulation factors in liver failure?

A

Coagulation factors are reduced

26
Q

What are the four clotting factors?

A

II, VII, IX and X

2,7,9 and 10

27
Q

Where is vitamin K absorbed?

What does it require for absorption?

A

Vitamin K is absorbed in the upper intestine

Requires bile salts for absorption

28
Q

What are some of the possible causes of vitamin K deficiency?

A

Warfarin

Diet/ malabsorption

Obstructive jaundice 
(e.g pancreatic cancer)

Haemorrhagic disease of the newborn

29
Q

Why does DIC occur?

A

All the clotting factors are used up in thrombus formation

30
Q

What are some of the possible causes of DIC?

A

Sepsis

Obstetric emergencies

Malignancy

Hypovolaemic shock (hypoxia causes tissue damage)

31
Q

How is DIC managed?

A

Treat the underlying cause (e.g antibiotics or removing the placenta)

Platelets and plasma transfusions and fibrinogen replacement

32
Q

What mode of inheritance does haemophilia involve?

A

X-linked inheritance

only affects males

33
Q

Where are the most common sited of bleeding in haemophilia?

A

Ankle, knee and elbow joints

These sites take a lot of strain and get a lot of bumps

34
Q

Is haemophilia A or B more common?

A

Haemophilia A is most common

35
Q

Which coagulation factor deficiencies do haemophilia A and B involve?

A

Haemophilia A - factor VIII deficiency

Haemophilia B - factor IX deficiency

36
Q

What are some of the clinical features of haemophilia?

A

Recurrent haemarthroses (blood in the joint – very painful and limits movement

Recurrent soft tissue bleeds (e.g bruising in toddlers)
Tend to bleed into big muscles e.g iliopsoas

Prolonged bleeding after dental extractions, surgery and invasive procedures

37
Q

How is haemophilia managed?

A

Infusions of factor VIII

Joint replacements

38
Q

Which class of drugs are arterial Vs venous thrombotic events treated with?

A

Arterial - anti-platelets

Venous - anti-coagulants

39
Q

Is venous thrombosis a problem of primary or secondary haemostasis?

A

Problem of secondary haemostasis - involves the formation of a fibrin clot

40
Q

What are the components for Virchow’s Triad?

A

Stasis

vessel wall (valve problems)

Hypercoagulability

41
Q

What is the strongest risk factor for venous thromboembolism?

A

Having had a previous DVT or PE

42
Q

What is thrombophilia?

A

Familial or acquired disorders which predispose to thrombosis

43
Q

Give some examples of hereditary thrombophilias

A

Factor V Leiden

Antithrombin deficiency

Protein C or S deficiency

44
Q

What are the indications for screening for thrombophilia?

A

Venous thrombosis at <45 years old

Recurrent or unusual venous thrombosis

FH of venous thrombosis or thrombophilia

45
Q

What are the components of antiphospholipid antibody syndrome?

A

Recurrent thromboses

Recurrent miscarriage

Mild thrombocytopenia

46
Q

How is antiphospholipid syndrome managed?

A

Aspirin / Warfarin

(can get venous or arterial thrombosis)

*Heparin should be used in pregnancy

47
Q

Is arterial thrombosis a problem of primary or secondary haemostasis?

A

Arterial thrombosis is a problem of primary haemostasis - involves the formation of a platelet rich thrombus

48
Q

How do platelets bind to sub endothelial collagen?

platelet adhesion

A

Via glycoprotein 1b and VWF

49
Q

How doe platelets attach to eachother?

platelet aggregation

A

Via GPIIbIIIa and fibrinogen

50
Q

An isolated prolonged partial thromboplastin time selects a deficiency of factors in which pathway?

A

The intrinsic pathway

51
Q

Factor VIII deficiency is a deficiency in which pathway?

A

The intrinsic pathway

52
Q

An isolated prolonged prothrombin time reflects a deficiency of factors involved in which pathway?

A

The extrinsic pathway

53
Q

Deficiencies in common pathway factors cause a prolongation of both the prothrombin time and the activated partial thromboplastin time. Which clotting factors are involved in the common pathway?

A

II, V and X

54
Q

Factor VII deficiency is a deficiency in which pathway?

A

The extrinsic pathway

HAEMATOLOGY (10 decks)

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